1. Field of the Invention
The present invention relates to a vehicle equipped with a leanable body frame and two front wheels.
2. Description of the Related Art
A vehicle described in, for example, International Patent Publication No. 2014/065396 includes a body frame that leans to the left or right of the vehicle when the vehicle turns left or right and two front wheels that are arranged side by side in a left-right direction of the body frame. This type of vehicle is able to turn with its body frame leaning from a vertical direction. More specifically, the body frame leans to the right of the vehicle when the vehicle turns to the right, while when the vehicle turns to the left, the body frame leans to the left of the vehicle. In this type of vehicle, a distance between the two front wheels which are arranged side by side in the left-right direction of the body frame is very short, compared with a general four-wheeled vehicle. Consequently, this type of vehicle is compact in size in relation to the left-right direction of the body frame.
The vehicle described in International Patent Publication No. 2014/065396 includes a so-called parallelogram type linkage. The parallelogram type linkage can be disposed above the two front wheels. On the other hand, a linkage that is known as a double wishbone type linkage is disposed between the two front wheels in the left-right direction of the body frame. Accordingly, the vehicle equipped with the parallelogram type linkage is more compact in size in relation to the left-right direction of the body frame than the vehicle equipped with the double wishbone type linkage.
The parallelogram type linkage includes an upper cross member, a lower cross member, a left side member and a right side member. The upper cross member, the lower cross member, the left side member and the right side member are connected so that the upper cross member and the lower cross member maintain postures parallel to each other and the left side member and the right side member maintain postures parallel to each other. The upper cross member and the lower cross member are supported on the body frame so as to turn about axes that extend in a front-rear direction of the body frame. The left side member is supported at a left portion of the upper cross member and a left portion of the lower cross member so as to turn abut axes that extend in the front-rear direction of the body frame. The right side member is supported at a right portion of the upper cross member and a right portion of the lower cross member so as to turn about axes that extend in the front-rear direction of the body frame. Namely, the upper cross member, the lower cross member, the left side member and the right side member turn individually about the axes that extend in the front-rear direction of the body frame. Accordingly, movable ranges of the upper cross member, the lower cross member, the left side member and the right side member when the parallelogram type linkage operates are relatively small in relation to a front-rear direction of the vehicle.
The vehicle described in International Patent Publication No. 2014/065396 includes a telescopic suspension. The telescopic suspension includes a left suspension and a right suspension. The left suspension supports one (a left front wheel) of the two front wheels at a lower portion thereof and is supported on the left side member at an upper portion thereof. The left suspension attenuates an upward displacement of the left front wheel in an up-down direction of the body frame relative to the upper portion thereof. The right suspension supports the other (a right front wheel) of the two front wheels at a lower portion thereof and is supported on the right side member at an upper portion thereof. The right suspension attenuates an upward displacement of the right front wheel in the up-down direction of the body frame relative to the upper portion thereof. The telescopic suspension includes an inner tube and an outer tube. The inner tube and the outer tube are displaced relatively along a telescopic axis that extends in the up-down direction of the body frame. Accordingly, movable ranges of the inner tube and the outer tube when the telescopic suspension operates are relatively small in the front-rear direction of the vehicle.
Consequently, the vehicle including the parallelogram type linkage and the telescopic suspension is compact in size in the front-rear direction.
In the vehicle described above, it is desired that a maximum displacement amount (hereinafter, referred to as a stroke) of the suspension is increased. In a case where the inner tube and the outer tube are long in the up-down direction of the body frame, the stroke can be increased accordingly. However, the vehicle is increased in size in the up-down direction.
Additionally, it is desired that a maximum leaning angle (hereinafter, referred to as a maximum banking angle) of the body frame is increased. In a case where a space between a left member that includes the left suspension and the left front wheel and a right member that includes the right suspension and the right front wheel in the left-right direction of the body frame is increased, it becomes difficult for the left member and the right member to interfere with each other even when the body frame is caused to lean. In other words, the maximum banking angle can be increased by increasing the space between the left member and the right member in the left-right direction of the body frame. In a case where the space between the left member and the right member in the left-right direction of the body frame is expanded, however, the space between the left side member that supports the left suspension and the right side member that supports the right suspension in the left-right direction of the body frame is expanded. This increases the size of the vehicle in the left-right direction. In addition, distances from the turning centers of the upper cross member and the lower cross member about which they turn relative to the body frame to the left side member and the right side member become long. Accordingly, the movable range of the linkage becomes wide not only in the left-right direction but also in the up-down direction of the body frame. Consequently, the vehicle is also increased in size in the up-down direction.